The Massachusetts State Police have assigned investigators to look into several threats that have been made against staff from the state’s child-protection agency by people who are angry at its handling of the custody controversy surrounding 15-year-old Justina Pelletier.

David Procopio, spokesman for the State Police, confirmed Friday that the Department of Children and Families has given them about a dozen threatening communications to staff, which came through e-mail, telephone, social media, fax, or comments on news stories.

“We’ve compiled them and assigned them to a unit that specializes in threats, especially those sent electronically,” Procopio said.

He said they will be assessed to see if they do pose a danger and if investigators can identify the source. He also acknowledged that state troopers helped escort Pelletier to her weekly visit with her parents Friday. That was done, said someone with close knowledge of the visit, after an individual contacted the transportation company that drives Justina to her weekly visit and threatened to kidnap her along the route.

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Procopio said the senders of the threatening messages did not say specifically what they would do, but suggested something along the lines of “retribution or consequences” for their role in the Pelletier case.

The threats have not been confined to DCF staff. In one online communication sent in the past week, a group listed the home address of Juvenile Judge Joseph Johnston and one of the physicians involved in the case, although it mostly urged people to write or call them. The group also said that the agency should know that “failure to comply will result in retaliation which you will not be able to withstand. Free Justina and return her home to her family.”

Others in state government have been on the receiving end of a massive letter-writing and phone-calling campaign generated by groups supporting the Pelletier parents. Since the start of the year, several national conservative Christian groups have gotten involved in this case, seeing it as an example of government intrusion on parental rights.

Pelletier’s parents could not be reached last night, but their spokesman, the Rev. Patrick Mahoney, said any threats or intimidations “must be condemned.”

DCF spokeswoman Mary-Leah Assad said the threats began coming in full force over the past few weeks, but escalated in the past few days. On Tuesday, the judge issued a ruling that gave permanent custody of Justina to DCF, subject to review every six months, a decision that was a serious setback to the parents’ efforts to get their daughter back home.

Assad said the agency is taking the threats “very seriously.” She said the threats, especially if they include kidnapping Justina, threaten her safety, as well.

“We urge all those involved with this case to join us in speaking out against any circulation of threats or misleading information that is harmful to Justina’s well-being, her security, and the security of those around her,” she said in a written statement.

This case, which has drawn national attention, involves the concept of medical child abuse.

Pelletier’s parents, who live in West Hartford, Conn., have insisted that their daughter suffers from mitochondrial disorder, a group of genetic ailments that affect how cells produce energy, often causing problems with the gut, brain, and muscles. Pelletier’s physicians at Tufts Medical Center had been treating her for that illness for about a year, saying she exhibited many of its symptoms, and they were still in the midst of determining if she had a clear-cut case of the disorder.

In February 212, Pelletier was brought to Children’s Hospital after suffering severe intestinal issues and after she started having profound trouble walking. Doctors there concluded in a matter of a few days that her problems were primarily psychiatric and that the parents were ignoring the root cause of her problems and pushing for unnecessary medical interventions.

When the parents sought to have their daughter discharged, the hospital filed medical child abuse charges, which were ultimately supported by DCF and later a juvenile court judge. On Tuesday, the judge said he believes the girl suffers from primarily psychiatric issues based on his review of testimony.

As one compromise measure, DCF and the judge have agreed to allow Pelletier’s medical and psychiatric care to be handled by Tufts, starting as soon as this week, an acknowledgment that Tufts is the hospital the parents preferred all along and that it would be best to end the parents’ antagonistic relationship with Children’s Hospital.

Also Friday, the House Republican leadership sent a letter to Governor Deval Patrick asking him to “open the line of communication” with Governor Dannel Malloy of Connecticut and “work to facilitate the safe and prompt return of Justina to Connecticut.”

The lawmakers’ letter comes largely in response to the ruling by Johnston this week, in which he also urged stepped-up efforts to get the girl’s clinical and legal case transferred back to her home state. Johnston’s written ruling rebuked the Connecticut Department of Children and Families for failing to get more involved in taking custody of the teenager.

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